U.S. patent application number 16/460914 was filed with the patent office on 2019-10-24 for burst throttling for multi-tenant storage services.
The applicant listed for this patent is Amazon Technologies, Inc.. Invention is credited to Marc John Brooker, Bei-Jing Guo, Norbert Paul Kusters, Marc Levy, John Robert Smiley.
Application Number | 20190324812 16/460914 |
Document ID | / |
Family ID | 59257026 |
Filed Date | 2019-10-24 |
![](/patent/app/20190324812/US20190324812A1-20191024-D00000.png)
![](/patent/app/20190324812/US20190324812A1-20191024-D00001.png)
![](/patent/app/20190324812/US20190324812A1-20191024-D00002.png)
![](/patent/app/20190324812/US20190324812A1-20191024-D00003.png)
![](/patent/app/20190324812/US20190324812A1-20191024-D00004.png)
![](/patent/app/20190324812/US20190324812A1-20191024-D00005.png)
![](/patent/app/20190324812/US20190324812A1-20191024-D00006.png)
![](/patent/app/20190324812/US20190324812A1-20191024-D00007.png)
![](/patent/app/20190324812/US20190324812A1-20191024-D00008.png)
United States Patent
Application |
20190324812 |
Kind Code |
A1 |
Kusters; Norbert Paul ; et
al. |
October 24, 2019 |
BURST THROTTLING FOR MULTI-TENANT STORAGE SERVICES
Abstract
Burst throttling methods may be used to manage computing
resources of a data storage service. Tokens may represent I/O
operations executed by a customer of the data storage service. A
first token bucket may contain a set of tokens representing the
overall I/O operation capacity of the data storage service.
Additionally, a second token bucket may contain a set of tokens for
a given logical volume maintained by the data storage service. When
I/O requests are received tokens may be charged the first token
bucket and the second token bucket. Furthermore, if there is
sufficient capacity, the data storage service may charge a reduced
number of tokens to the third token bucket.
Inventors: |
Kusters; Norbert Paul;
(Redmond, WA) ; Smiley; John Robert; (Issaquah,
WA) ; Brooker; Marc John; (Seattle, WA) ; Guo;
Bei-Jing; (Seattle, WA) ; Levy; Marc;
(Seattle, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Amazon Technologies, Inc. |
Seattle |
WA |
US |
|
|
Family ID: |
59257026 |
Appl. No.: |
16/460914 |
Filed: |
July 2, 2019 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15645909 |
Jul 10, 2017 |
10387200 |
|
|
16460914 |
|
|
|
|
14675576 |
Mar 31, 2015 |
9703602 |
|
|
15645909 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 2209/503 20130101;
G06F 9/5011 20130101; G06F 3/0656 20130101; G06F 9/50 20130101;
G06F 3/061 20130101; G06F 9/4881 20130101; G06F 2209/504 20130101;
Y02D 10/00 20180101; G06F 3/067 20130101; Y02D 10/22 20180101 |
International
Class: |
G06F 9/50 20060101
G06F009/50; G06F 3/06 20060101 G06F003/06; G06F 9/48 20060101
G06F009/48 |
Claims
1. A computer-implemented method, comprising: for a data storage
request to be performed by a data storage service utilizing
computing resources of the data storage service, determining a
value for an amount of computing resources to be used by the data
storage service to process the data storage request; removing the
value from a first amount of operations allocated to a logical
volume by the data storage service; determining a reduced value to
remove from a second amount of operations allocated to the logical
volume based at least in part on an amount of operations remaining
in the first amount of operations after removing the value;
removing the value from a total amount of operations representing a
capacity of the computing resources to perform operations of the
data storage service; and processing the data storage request.
2. The computer-implemented method of claim 1, wherein the
computer-implemented method further comprises delaying processing
of the data storage request as a result of determining there are
insufficient operations in the first amount of operations to remove
the value.
3. The computer-implemented method of claim 1, wherein the
computer-implemented method further comprises determining the first
amount of operations allocated to the logical volume based at least
in part on an analysis of a workload associated with the logical
volume.
4. The computer-implemented method of claim 1, wherein determining
the reduced value further comprises increasing the second amount of
operations allocated to a logical volume.
5. A system, comprising: one or more processors; and memory that
includes instructions that, as a result of being executed by the
one or more processors, cause the system to: determine a value
representing an amount of computing resources to be utilized by the
system to process a request to perform an operation on a logical
volume; process the request by at least: removing the value from a
first set of credited operations associated with the logical
volume; determining a reduced value to remove from a second set of
credited operations associated with the logical volume; and
determining there are sufficient credited operations remaining in
the first set of credited operations and the second set of credited
operations after removing the value and reduced value; and remove
the value from a third set of credited operations representing a
total capacity of the system to process requests.
6. The system of claim 5, wherein the value represents a number of
input/output (I/O) operations performed to process the request.
7. The system of claim 5, wherein the first set of credited
operations further includes a set of tokens, where a token of the
set of tokens represents an I/O operation.
8. The system of claim 5, wherein the second set of credited
operations is determined based at least in part on a number of
credited operations of the third set of credited operations.
9. The system of claim 5, wherein the second set of credited
operations is determined based at least in part on a size of the
logical volume.
10. The system of claim 5, wherein the second set of credited
operations is determined based at least in part on a number of
operations per interval of time requested by a customer associated
with the logical volume.
11. The system of claim 5, wherein the second set of credited
operations is determined based at least in part on a number of
credited operations remaining in the first set of credited
operations after removing the value from the first set of credited
operations.
12. The system of claim 5, wherein the reduced value is determined
based at least in part on a percentage of the total capacity of the
system to process the request.
13. A non-transitory computer-readable storage medium having stored
thereon executable instructions that, as a result of being executed
by one or more processors of a computer system, cause the computer
system to at least: determine a first representation of an amount
of computing resources of the computer system to be utilized to
process a work request associated with a storage location; remove
the first representation from a second representation of computing
resources, the second representation of computing resources
indicating a total amount of computing resources of the computer
system currently available; remove the first representation from a
third representation of computing resources, the third
representation of computing resources indicating an amount of
computing resources associated with processing work requests
associated with the storage location; remove an alternative
representation from a fourth representation of computing resources,
the fourth representation of computing resources indicating an
increased amount of computing resources associated with processing
work requests associated with the storage location over an interval
of time; and process the work request.
14. The non-transitory computer-readable storage medium of claim
13, wherein the instructions that cause the computer system to
remove the alternative representation from a fourth representation
of computing resources further include instructions that cause the
computer system to determine the alternative representation based
at least in part on a number of computing resources included in the
fourth representation of computing resources.
15. The non-transitory computer-readable storage medium of claim
13, wherein the instructions further comprise instructions that,
when executed by the one or more processors, cause the computer
system to delay processing of the work request.
16. The non-transitory computer-readable storage medium of claim
15, wherein the instructions that cause the computer system to
delay processing of the work request further include instructions
that cause the computer system to delay processing of the work
request as a result of the third representation of computing
resources including insufficient capacity to process the work
request after removing the first representation.
17. The non-transitory computer-readable storage medium of claim
15, wherein the instructions that cause the computer system to
delay processing of the work request further include instructions
that cause the computer system to delay processing of the work
request as a result of the second representation of computing
resources including insufficient capacity to process the work
request after removing the first representation.
18. The non-transitory computer-readable storage medium of claim
15, wherein the instructions further comprise instructions that,
when executed by the one or more processors, cause the computer
system to: after delaying the work request, determine insufficient
capacity in the third representation of computing resources to
process the work request; and perform a secondary throttling
mechanism on the work request.
19. The non-transitory computer-readable storage medium of claim
13, wherein the instructions further comprise instructions that,
when executed by the one or more processors, cause the computer
system to: determine insufficient capacity in the second
representation of computing resources to process the work request;
and as a result, remove the first representation from the fourth
representation of computing resources.
20. The non-transitory computer-readable storage medium of claim
13, wherein the instructions further comprise instructions that,
when executed by the one or more processors, cause the computer
system to: determine insufficient capacity in the third
representation of computing resources to process the work request;
and as a result, remove the first representation from the fourth
representation of computing resources.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/645,909, filed Jul. 10, 2017, entitled
"BURST THROTTLING FOR MULTI-TENANT STORAGE SERVICES," which is a
continuation U.S. patent application Ser. No. 14/675,576, filed
Mar. 31, 2015, now U.S. Pat. No. 9,703,602, entitled "BURST
THROTTLING FOR MULTI-TENANT STORAGE SERVICES," the disclosures of
which are hereby incorporated herein in their entirety.
BACKGROUND
[0002] Several leading technology organizations are investing in
building technologies that provide customers with access computing
resources. Such services provide access to computing and/or storage
resources (e.g., storage devices providing either a block-level
device interface, or a web service interface) to customers or
subscribers. Within multi-tier ecommerce systems, combinations of
different types of resources may be allocated to customers and/or
their applications, such as whole physical or virtual machines,
CPUs, memory, network bandwidth, or I/O capacity. Block-level
storage devices implemented at storage service may be made
accessible, for example, from one or more physical or virtual
machines implemented by another service.
[0003] Computer systems that provide services to customers may
employ various techniques to protect the computer systems from an
overwhelming number of service requests that could potentially
overload the computer systems. In general, a computer system is
considered to be in an "overloaded" state if it is not able to
provide the expected quality of service for at least some portion
of customer requests it receives. Common solutions applied by
overloaded computer systems include denying service to customers or
throttling a certain number of incoming requests until the computer
systems get out of an overloaded state. Such techniques may for
example be employed at storage servers in some embodiments on a
per-storage-device level.
[0004] Some current computer systems avoid an overload scenario by
comparing the request rate with a fixed global threshold and
selectively refusing service to customers once this threshold has
been crossed. However, it is difficult, if not impossible, to
define a single global threshold that is meaningful (much less that
provides acceptable performance) in a computer system that receives
different types of requests at varying, unpredictable rates, and
for which the amount of work required to satisfy the requests is
also varying and unpredictable in at least some cases. While many
services may have been designed to work best when client requests
are uniformly distributed over time, in practice such temporal
uniformity in work distribution is rarely encountered. Computing
resource service providers that wish to achieve and retain high
levels of customer satisfaction may need to implement techniques
that deal with temporal and spatial workload variations in a more
sophisticated manner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Various embodiments in accordance with the present
disclosure will be described with reference to the drawings, in
which:
[0006] FIG. 1 illustrates aspects of an admissions control
mechanism that utilizes a global work token bucket in combination
with work token buckets to schedule operations, according to an
embodiment;
[0007] FIG. 2 illustrates aspects of an admissions control
mechanism that utilizes a global work token bucket in combination
with work token buckets to schedule operations, according to an
embodiment;
[0008] FIG. 3 shows an illustrative process which may be used to
determine a reduced number of work tokens to charge for a work
request in at least one embodiment;
[0009] FIG. 4 illustrates configuration properties of a token
bucket, such as the global token bucket or work token bucket, which
may be used for implementing various types of admissions control
policies, according to at least one embodiment;
[0010] FIG. 5 shows an illustrative example of a data storage
service in accordance with various embodiments;
[0011] FIG. 6 illustrates an environment in which various aspects
of admissions control-related operations for block-level devices
that are attachable to one or more computer instances may be
implemented, according to at least one embodiment;
[0012] FIG. 7 illustrates an environment in which various aspects
of admissions control-related operations for block-level devices
that are attachable to one or more computer instances may be
implemented, according to at least one embodiment; and
[0013] FIG. 8 illustrates an environment in which various
embodiments can be implemented.
DETAILED DESCRIPTION
[0014] In the following description, various embodiments will be
described. For purposes of explanation, specific configurations and
details are set forth in order to provide a thorough understanding
of the embodiments. However, it will also be apparent to one
skilled in the art that the embodiments may be practiced without
the specific details. Furthermore, well-known features may be
omitted or simplified in order not to obscure the embodiment being
described.
[0015] Techniques described and suggested herein relate to
improvements to burst-throttling methods for multi-tenant
block-level data storage services. A data storage service may be
provided by a computing resource service provider, and the data
storage service may use one or more network attached storage
devices, such as block-level storage devices, to provide data
storage for customers of the computing resource service provider.
In order to reduce the cost of the computing resources, such as the
block-level storage devices, provided to the customers of the
computing resource service provider, computer systems providing the
customers with access to the computing resources may be
"oversubscribed." Oversubscribing computing resources may include
offering more of the computing resource to customers than there is
actually physical capacity for on the computer systems providing
the computing resources to the customers. In general, a customer
may not consume the entire portion of the computer systems
resources allocated to the customer. Oversubscription may enable
the computing resource service provider to increase efficiency and
reduce the amount of un-utilized or under-utilized computing
resources made available to customers. When computing resources of
the computer system are oversubscribed, the computer system may
become overloaded when multiple customers attempt to consume the
entire portions of their allotted computing resources at or near
the same time. Throttling techniques described herein may be used
to prevent the computer system from being overloaded while enabling
the customers to continue to receive a high level of
performance.
[0016] For example, the data storage service may provide the
customers with access to block-level storage devices allowing the
customer a certain number of Input/Output Operations per Second
(IOPS). The data storage service may enable burst allocation of
resources enabling customers with spikey workloads (e.g., workloads
of varying sizes and intervals) to receive greater performance when
required. For example, burst allocation may provide up to 3,000
IOPS for 30 minutes in order to provide better performance during
particular workloads, such as during boot operations or accessing
large files. A certain level of burst allocation may be provided
regardless of the size of the block-level storage volume. For
example, a burst allocation of 3,000 IOPS for 30 minutes may be
provided for volumes of 1 Gigabytes (Gb) or 300 Gb. The data
storage service may analyze customer workload and determine a
particular amount of computing resources to allocate to the
customer during burst allocation.
[0017] In order to provide the customer with computing resources
during burst allocation a burst token bucket model may be used. The
burst token bucket model may allocate customers a certain number of
tokens. Each token may represent an "I/O credit" that may be used
by the customer to perform one read or one write operation. For
example, a token may be removed from a burst token bucket
associated with a particular customer for each I/O operation
requested by the customer and performed by the data storage
service. Additionally, the tokens may correspond to a particular
size I/O operation. For example, a token may correspond to a 4 kb
I/O operation. In this example, one read or write operation may be
a 4 kb I/O operation. Therefore, if the customer submits a request
including a 16 kb I/O operation, processing the request may require
4 work tokens. A particular burst token bucket may be associated
with each customer volume and the burst token bucket may hold up to
a maximum number of tokens (e.g., a burst token bucket may hold up
to 5 million tokens). The burst token buckets may be initially
allotted a certain number of tokens and/or may accumulate tokens
over time and at a certain rate. For example, tokens may accumulate
at a rate of 3 tokens per configured Gb per second, up to the
maximum capacity of the burst token bucket. Additionally, the
customer may be able to use tokens up to a maximum rate. The
customer may use tokens by providing the data storage service with
a request to perform I/O operations and the data storage service
preforming the I/O operations on behalf of the customer. For
example, a customer may be able to spend tokens at a rate up to
3,000 tokens per second per volume which equates to a maximum IOPS
rate of 3,000. This maximum IPOS rate may be considered that
maximum performance level of the volume and the baseline
performance level of the volume may be equal to the rate at which
tokens are accumulated (e.g., returning to the example above the
fill rate of 3 tokens per Gb per second or 3 IOPS per Gb per
second). Tokens may be first removed from the bust token bucket and
then if there is insufficient capacity in the burst token bucket a
secondary throttling mechanism may be used.
[0018] For example, the data storage service may maintain a global
work token bucket. The global work token bucket may correspond to
the total capacity of the computer systems operating the logical
volumes on behalf of the customers. For example, a particular
computer system may have a maximum capacity of 10,000 IOPS.
Therefore, the global token bucket when the system has 0 percent
load may contain 10,000 tokens. When a customer request including
an I/O operation is received at the data storage service a number
of tokens equaling the I/O operations may be removed from the
global token bucket. For example, if the customer request includes
a 32 kb I/O operation, a number of tokens equaling 32 kb may be
removed from the global work token bucket (e.g., if the token size
is 16 kb two tokens may be removed). Once the tokens are removed
from the global work token bucket, the data storage service may
attempt to remove tokens from the work token bucket associated with
the logical volume.
[0019] As described above, each logical volume may have associated
with it a burst token bucket associated with an amount of allocated
computing resources available to the logical volume. When an I/O
request is received at the data storage service, a token may be
removed from the burst token bucket and the global token bucket if
there is sufficient capacity in each. If there is insufficient
capacity in the burst token bucket, a token may be removed from the
global work token bucket and another token may be removed from a
work token bucket associated with the volume. The burst token
bucket may operate as an initial throttling mechanism and if the
burst token bucket is empty or below a threshold capacity a second
throttling mechanism may be used. For example, a number of tokens
corresponding to the received I/O request may be removed from the
burst token bucket corresponding to a logical volume indicated in
the received I/O request and a global token bucket indicative of
the overall load on the system processing the I/O request. However,
if the burst token bucket does not have sufficient tokens to remove
the number of tokens corresponding to the received I/O request
(e.g., if after removing the number of tokens the burst token
bucket would have less than zero tokens or less than some threshold
value) the system may delay processing the request based at least
in part on a fill rate of the burst token bucket. After delaying
the request, if the burst token bucket still have insufficient
tokens, the tokens may be removed from a work token bucket
associated with the logical volume indicated in the request.
[0020] In various embodiments, fewer tokens than the number of
tokens removed from the global token bucket are removed from the
work token bucket for the volume in order to allow the logical
volume to achieve greater performance (e.g., allowing the customer
to use fewer tokens for the same amount of work request if the
server has additional capacity). For example, a customer may
provide an I/O request equaling one token to the data storage
service, and the data storage service may remove one token from the
global work token bucket and 1/3 of a token from the work token
bucket for the logical volume. The amount of tokens charged the
customer for a particular I/O request or set of I/O requests may be
dynamically determined based on a variety of factors including the
load on the data storage service, the level of performance
allocated to the customers, the type of I/O request (e.g.,
sequential or non-sequential), and other factors described in
greater detail below.
[0021] FIG. 1 illustrates an environment 100 in which an admissions
control mechanism utilizes a global work token bucket 102 in
combination with burst token bucket 106 to schedule operations,
according to an embodiment. Generally speaking, such mechanisms may
be used for workload management of various types of activities,
such as storage objects, database tables, database partitions, and
other workloads that include the partitioning and/or allocation of
computing resources. In the context of a block storage service,
such buckets may be maintained for various volumes or volume
partitions by one or more admissions controllers 116, at either an
instance host, storage server, or both. For example, the admissions
controller 116 may be a set of computer instructions or other logic
configured to maintain state information corresponding to the
storage server in a memory of the storage server. The state
information including a mechanism that uses a single global work
token bucket 102 of tokens is illustrated in FIG. 1 for simplicity
of presentation; however, combinations of multiple global work
token buckets may be used in some embodiments, such as one bucket
for read operations and a different bucket for write operations. In
addition to the global work token bucket 102, the mechanism may
include a set of burst token buckets 106 and a set of work token
buckets 104, and each burst token buckets 106 and work token bucket
104 may correspond to a logical volume or partitioned volume
implemented by the storage server.
[0022] A global work token bucket 102, a burst token buckets 106
and a work token bucket 104 (e.g., a logical container which may be
implemented as a data structure within a software program) set up
for admissions control purposes associated with a particular
storage server or entity of the storage server, such as a
block-level storage device (e.g., a volume, or a portion of a
volume) may be populated with an initial set of tokens during
bucket initialization or server initialization. The initial
population may be determined, e.g., based on expectations of the
workload, service level agreements, a provisioning budget specified
by the client that owns or manages the corresponding data object,
or some combination of such factors in various embodiments. For
some types of buckets the initial population may be set to zero in
some embodiments. In some implementations the initial population of
a bucket may be set to a maximum population for which the bucket is
configured. The global work token bucket 102 may be populated with
a number of tokens equal to the maximum capacity of the storage
server.
[0023] When an indication of a new work request 114 (such as a read
request or a write request in the case of a storage object or
database object) is received at an admissions controller 116, the
admissions controller 116 may attempt to determine whether some
number N of tokens 108 (where N may be greater than or equal to 0,
depending on implementation or on configuration parameters) are
present in the burst token bucket 106. Then the admissions
controller may attempt to determine whether some number N of tokens
(where N may be greater than or equal to 1, depending on
implementation or on configuration parameters) are present in the
global work token bucket 102 in the depicted embodiment. If that
number of tokens is available in the burst token bucket 106 and the
global work token bucket 102, the work request 114 may be accepted
or admitted for execution immediately, and the tokens may be
consumed or removed from both the burst token bucket 106 and the
global work token bucket 102. Otherwise, if N tokens are not
present, the acceptance of the work request 114 may be deferred
until sufficient tokens become available in the depicted
embodiment. In the illustrated scenario, work request 118 has been
accepted and completed, work request 120 has been deferred and
queued, and other work requests 114 are yet to be considered by the
admissions controller 116.
[0024] The deferred work request may eventually be accepted, when
sufficient tokens eventually become available in both the work
token bucket 104 and the global work token bucket 102 or
alternatively when sufficient tokens eventually become available in
both the burst token bucket 106 and the global work token bucket
102. In some embodiments, if a particular work request does not get
accepted within some timeout window, it may be rejected by the
admissions controller. Rejected work requests may be resubmitted or
retried in some implementations. In at least some embodiments, if
sufficient tokens are not available in the work token bucket 104
and/or the global work token bucket 102, when the work request is
processed by the admissions controller 116, the work request may be
rejected immediately instead of being deferred.
[0025] As shown by FIG. 1, the burst token bucket 106, the work
token bucket 104, and the global work token bucket 102 may be
refilled or repopulated over time, e.g., based on configuration
parameters, such as a refill rate associated with the bucket, as
described below with reference to FIG. 4. In some implementations,
token refill operations may accompany, or be performed in close
time proximity to, consumption operations (e.g., within a single
software routine, N tokens may be consumed for admitting a request,
and M tokens may be added based on the refill rate and the time
elapsed since the bucket was last refilled). Refill rates or token
counts of a given work token bucket 104 and/or burst token bucket
106 may be modified by client-side components of a storage service,
e.g., to allow higher work request rates to be handled, typically
for short time intervals. Limits may be placed on the maximum
number of tokens a work token bucket 104 and/or burst token bucket
106 may hold in some embodiments, and/or on the minimum number of
tokens, e.g., using configuration parameters. Using various
combinations of configuration parameter settings, fairly
sophisticated admissions control schemes may be implemented in
different embodiments.
[0026] In one simple example scenario, to support a steady load of
100 work requests per second, work token bucket 104 of FIG. 1 may
be configured with an initial population of 100 tokens, a maximum
allowable population of 100 tokens and a minimum of zero tokens; N
may be set to 1, and the refill rate may be set to 100 tokens per
second, and one token may be added for refill purposes (assuming
the maximum population limit is not exceeded) once every 10
milliseconds. As work requests 114 arrive, one token may be
consumed for each work request. If a steady-state workload at 100
work requests per second, uniformly distributed during each second,
is applied, the refill rate and the workload arrival rate may
balance each other. Such a steady-state workload may be sustained
indefinitely in some embodiments, given the bucket parameters
listed above.
[0027] In another example, to support an inconsistent or spiky
workload (e.g., workloads that vary in both frequency and
amplitude), burst token bucket 106 of FIG. 1 may be configured with
an initial population of 0 tokens and a fill rate based at least in
part on the size of the logical volume or partition volume
associated with the bucket. For example, a fill rate of 3 tokens
per second per Gb may be applied to the burst token bucket 106.
Furthermore, the burst token bucket 106 may be configured to enable
a maximum number of tokens to be removed from the bucket per second
(e.g., 3,000 tokens per second may be removed from the bucket when
processing work requests 114). Additionally, the admissions
controller 116 may be configured to remove less than 1 token or a
fraction of a token per processed work request 114 to allow for
additional workload capacity to be allocated to logical volume or
partitioned volume. For example, the work token bucket may have a
maximum capacity of 1,000 tokens but the admissions controller 116
may be configured to remove 1/3 of a token per completed work
request 118 in order to allow the customer to burst the performance
of the logical volume or partitioned volume to 3,000 IOPS. While
the burst token bucket 106 may be configured, in various
embodiments, to consume less than 1 complete token, the global work
token bucket 102 may still consume a complete token. In this way
the total system capacity of the storage server may be reflected in
the global work token bucket 102. For each work request 114, the
admissions controller 116 may remove N tokens from the global work
token bucket 102 and some number less than N from the burst token
bucket 106. As described above, if either the burst token bucket
106 or the global work token bucket 102 does not contain sufficient
tokens to process the work request 114, the request may be delayed
or queued until both the work token bucket 104 and the global token
bucket contain sufficient tokens.
[0028] If, extending the above example, the arrival rate and/or the
refill rate is not uniform, scenarios may arise in which the burst
token bucket 106 or the global work token bucket 102 remains empty
for some (typically small) time intervals (e.g., if some set of
work requests in rapid succession consumes more tokens than the
refill mechanism is able to replace). In such a case, an arriving
work request may have to be rejected (or retried after a delay). In
order to deal with temporal non-uniformity of workloads without
introducing substantial delays or high rejection rates, various
techniques may be employed in different embodiments, such as the
temporary modifications of admissions control parameters by
client-side components.
[0029] FIG. 2 illustrates aspects of an admissions control
mechanism that utilizes a global work token bucket in combination
with burst token buckets and work token buckets to schedule
operations, according to an embodiment. As described above, the
admissions control mechanism may be used to allocate resources of a
storage server between various volumes or partitioned volumes
operated by customers of a computing resource service provider. A
global token bucket 202, a burst token bucket 206 and a work token
bucket 204 (e.g., a logical container which may be implemented as a
data structure within a software program) set up for admissions
control purposes associated with a particular storage server or
entity of the storage server, such as a block-level storage device,
may be populated with an initial set of tokens 208 during bucket
initialization or server initialization. As illustrated in FIG. 2,
an admissions controller 216 may process work request 214 by at
least charging or removing work tokens 208 from the global work
token bucket 202, burst token bucket 206, or the work token bucket
204. The admissions controller 216 may be executable instructions
executed by one or more processors of the data storage as described
above.
[0030] In the example illustrated in FIG. 2, a work request 214 is
received at the admissions controller 216. The work request 214 may
be an I/O operation, such as a read or write operation. The work
request 214 may include volume identification information, an
offset, and a length. The information included in the work request
214 may enable the admissions controller 216 to determine a number
of tokens 208 to remove from the burst token bucket 206 and then
the global work token bucket 202 and the work token bucket 204 if
required. Additionally, in various embodiments, the information
included in the work request 214 enables the storage server to
perform that I/O operation. For example, the storage server may use
the volume identification information, the offset, and the length
to retrieve a data object from a storage device on behalf of the
customer.
[0031] Once the work request 214 is received by the admissions
controller 216, the admissions controller 216 may determine a
number N of tokens corresponding to a capacity of the data storage
server required to process the request. For example, a token may
represent a 16 kb I/O operation, therefore a work request 214
including a 16 kb read operation would cost a single token 208. In
various embodiments, the admissions controller 216 first removes
the number of tokens N from the burst token bucket 206, represented
by the arrow 220 in FIG. 2. In various embodiments, the admissions
controller 216 remove a number of tokens less than the number of
tokens N from the burst token bucket 206. The admissions controller
216 may then remove from the global work token bucket 202 the
number of work tokens 208 required to complete the work request
218, represented by the arrow 210 in FIG. 2. In various
embodiments, if there is insufficient capacity in the burst token
bucket 206 to remove the number of tokens N, the admissions
controller 216 may then determine a second number of tokens to
remove from the work token bucket 204. The admissions controller
216 may determine a reduced number of work tokens 208 to remove
from the work token bucket. If there is sufficient capacity in the
global token bucket 202, the admissions controller may determine,
based at least in part on a token consumption policy (described in
greater detail below in connection with FIG. 4), an amount of
tokens less than the amount of tokens removed from the global token
bucket 202 to remove from the work token bucket 204. This may
enable customers, when there is sufficient storage service
capacity, to receive a higher number of IOPS or the same number of
IOPS for a longer period.
[0032] As illustrated by the arrow 212 in FIG. 2, an actual number
of tokens corresponding to the work request 214 and a reduced
number of tokens may be obtained by the admissions controller. The
reduced number of tokens may be determined dynamically or may be
fixed. The reduced number of tokens may be determined based at
least in part on various attributes of the storage service, the
customer, and/or the volume. For example, the reduced number of
tokens may be based on a current capacity of the global work token
bucket 202, the size of the volume associated with the work token
bucket 204, or a number of IOPS purchased by the customer. In the
example illustrated in FIG. 2, the reduced number of tokens equals
0.33. For each work request 214 the reduced number of work tokens
may be dynamically determined. For example, a set of work requests
214 may be tracked and for each work request 214 that is sequential
a reduced number of work tokens may be charged. The reduced number
of tokens may be removed first from the burst token bucket 206 so
long as there is sufficient capacity and then from the work token
bucket once the capacity of the burst token bucket 206 has been
depleted. This may allow the customer to increase work rate for a
period of time after which the work rate may be reduced based at
least in part on a maximum work rate of the work token bucket.
[0033] FIG. 3 shows an illustrative process 300 which may be used
to determine a reduced number of work tokens to charge for a work
request in at least one embodiment. The process 300 may be
performed by any suitable system such as the admissions controller
described above in FIGS. 1 and 2 or any combination of systems or
component thereof such as the data storage service described above.
Returning to FIG. 3, in an embodiment, the process 300 includes
receiving a work request 302. The work request may be a request to
perform an I/O operation as described above or may be any operation
that requires an allocation of computing resources to an operation
to be performed by the computing resources. After receiving the
work request, the admissions controller or other system executing
process 300 may determine a actual work token value based at least
in part on a the received work request 304. For example, the actual
token value may be based at least in part on an amount of computing
resources required to process the request. In another example, if a
logical volume can burst up to 100 request per second, the work
token value may be 1/100 for the a particular request. In various
embodiments, a reduced number of tokens is based on a maximum burst
IOPS made available to the customer. In a specific example, if the
work token bucket contains a maximum of 1,000 tokens and the
maximum burst IOPS allotted to the customer is 3,000 IOPS, the
reduced amount charged for a token may be 1/3 of a token.
[0034] The admissions controller may then determine if there is
sufficient capacity to remove the determined number of token from
the burst token bucket 306. If there is insufficient capacity, the
admission controller may delay processing the work request for a
determine interval of time 308. The admissions controller may delay
processing the request based at least in part on a fill rate of the
burst token bucket and number of tokens to be removed from the bust
token bucket. If there is sufficient capacity in the burst token
bucket, the number of determined tokens may be removed from the
burst token bucket 310. The admissions controller or other system
executing process 300 may then remove, from the global token
bucket, the actual number of work tokens to be charged for
performing the work request 314. As described above, the work token
value may correspond to a percentage or amount of computing
resources required to be allocated in order to complete the
requested operation.
[0035] In certain variations to the process 300, if there is still
insufficient capacity in the burst token bucket after processing of
the request has been delayed for the determined amount of time, the
admission controller may initiate a second throttling mechanism.
Returning to FIG. 3, once determined number of work tokens has been
removed from the global work token bucket, the current capacity of
the global work token bucket may indicate the overall capacity of
the computer system processing the received work request.
Additionally, the level of the global work token bucket may
indicate whether the system is overloaded. The admissions
controller may then determine if there is sufficient capacity to
charge a reduced amount of work tokens 316.
[0036] The admissions controller may determine if there is
sufficient capacity based at least in part on an amount of tokens
in the global work token bucket. For example, if after removing the
work tokens from the global token bucket, as in step 314, there are
zero tokens remaining in the global token bucket the admissions
controller may determine that there is insufficient capacity to
charge the reduced work token amount. If there is insufficient
capacity in the global work token bucket, the admission controller
can remove the actual work token value from the work token bucket
318. Conversely, if one or more tokens remain in the global token
bucket after removing the actual work token value from the global
token bucket, the admissions controller may determine that there is
sufficient capacity to remove the reduced work token amount from
the work token bucket 322. The admissions controller may then
determine a reduced amount of work tokens 320 to be charged to the
work token bucket associated with the volume indicated in the
received work request. The reduced amount of work tokens may be
determined based at least in part on a variety of factors. For
example, the reduced number of tokens may be based on a minimum
number of IOPS allocated to the customer.
[0037] In some embodiments, the process 300, the capacity of the
burst token bucket and the global token bucket may be allowed to go
below zero to allow for removal of work tokens even if removing the
tokens would cause the number of tokens in the bucket to drop below
zero.
[0038] FIG. 4 illustrates example configuration properties 402 of a
token bucket, such as the burst token bucket 106. the global work
token bucket 102, or work token bucket 104 illustrated in FIG. 1,
which may be used for implementing various types of admissions
control policies, according to at least one embodiment. In some
implementations, the token bucket may be implemented as an
in-memory data structure of the admissions controller, and may be
written to persistent storage as needed. Such a data structure may
comprise fields representing the current token population, when the
population was last modified, and/or values for various parameters
and policies indicated in FIG. 4.
[0039] A token consumption policy 410 may indicate how tokens are
to be consumed for admissions control, and the timing of the
consumption (e.g., whether all the tokens are to be consumed prior
to accepting a work request, or whether some tokens may be consumed
later based on the actual amount of work performed for the accepted
request). In various embodiments, the token consumption policy 410
may indicate a reduced number of work tokens to be consumed and
when the reduced number of tokens may be consumed. For example, the
token consumption policy 410 may indicate a particular fraction of
a token that may be consumed when there is a sufficient number of
tokens remaining in the global token bucket. Additionally, the
token consumption policy 410 may include a formula or method for
dynamically calculating an amount of tokens to be consumed for a
give operation.
[0040] In some embodiments different numbers of tokens may be
consumed for different types of operations from a given bucket
based on its consumption policy--e.g., I/O operations may be
classified as "large" or "small", and different amounts of tokens
may be consumed based on the size of the I/O operation. In some
embodiments, a token consumption policy 410 may also specify a
decay-during-idle parameter indicating whether (and at what rate)
tokens are to be deleted from the bucket if the corresponding work
target is not targeted for work requests for some time, or a
transfer-upon-idle parameter indicating whether tokens should be
transferred from one bucket to another (e.g., from a bucket of a
lightly-used volume to a bucket of a more heavily-used volume) if
they are not used during some time interval. In one embodiment, a
staleness policy may be used to consume tokens that have not been
consumed for a specified time interval--e.g., each token may be
associated with a validity lifetime after which the token may no
longer be useful for admissions control purposes.
[0041] The bucket configuration properties 402 may also include an
initial token population parameter 406, as depicted in an
embodiment illustrated in FIG. 4, which indicates how many tokens
are to be placed in the bucket at startup or initialization. Token
refill policy 414 may indicate at what rate, and/or under what
circumstances, tokens are to be added to the bucket, e.g., to help
sustain a rate of work for which the work target associated with
the bucket has been configured. One or more of the parameters of
the bucket may be changed over time--e.g., a default refill rate
may apply to the bucket, but in order to accommodate
higher-than-provisioned rates, a higher non-default rate may be
used at least temporarily. As described above, the token refill
policy 414 may be based on a size of the volume or partitioned
volume. Furthermore, the token refill policy 414 may indicate
whether to track a number of tokens that are attempted to be added
to the bucket according to the fill rate but cannot be added
because the bucket is at or above a maximum population indicated by
a maximum bucket population parameter 418. For example, the data
storage service may track a number of tokens added to the burst
token bucket when the burst token bucket is full (e.g., if the bust
token bucket has a maximum capacity of 3,000 tokens the data
storage system may track the number of tokens that would have been
added according to the token refill policy 414 but are not due to
the maximum bucket population parameter 418).
[0042] The maximum bucket population parameter 418 may indicate the
maximum capacity of the bucket and the corresponding work target.
In some embodiments, different types of operations may have
different admissions control rules (e.g., reads may have different
rules than writes, or I/Os may have different rules based on the
amount of data read or written) and the types of operations for
which the bucket is to be used may be specified in applicable
operation types parameter 420. In at least some embodiments, one or
more pricing policies 422 that may be used to determine the amounts
that clients are to be charged for the use of the bucket's tokens
may be indicated in the bucket properties. In different
embodiments, only a subset of the example parameters shown in FIG.
4 may be employed, while in other embodiments, additional bucket
configuration parameters beyond those shown in FIG. 4 may be used.
Values and/or settings for various properties shown in FIG. 4, as
well as other admissions control settings, may be programmatically
set or modified (e.g., by the client-side components using web
service calls) in at least some embodiments. It is noted that
admissions control techniques that do not utilize work tokens may
be employed in at least some embodiments.
[0043] FIG. 5 shows an illustrative example of a data storage
service in accordance with at least one embodiment. The data
storage service 500 may be a service of a computing resource
provider used to operate a block-level data storage service such as
described above in connection with FIGS. 1 and 2. As illustrated in
FIG. 5, the data storage service 500 includes various subsystems
such as a request processing subsystem 502 and a management
subsystem 504. The data storage service 500 may also include a
plurality of data storage servers 506 and an admissions data 508,
which may store data about various global token buckets, burst
token buckets, and work token buckets associated with volumes
maintained by the data storage servers 506 as described above. In
an embodiment, the request processing subsystem 502 is a collection
of computing resources, such as webservers and application servers,
collectively configured to process requests submitted to the data
storage service 500. The request processing subsystem 502, for
example, may include one or more webservers that provide a web
service interface to enable customers of the data storage service
500 to submit requests to be processed by the data storage service
500. The request may include work requests 114 as described above
in connection with FIG. 1. The request processing subsystem 502 may
include computer systems configured to make various determinations
in connection with the processing of requests, such as whether
policy allows fulfillment of a request, whether requests are
authentic (e.g., electronically signed using a suitable
cryptographic key) and otherwise. In various embodiments, the
request processing subsystem 502 may include an admissions
controller as described above.
[0044] Components of the request processing subsystem may interact
with other components of the data storage service 500 (e.g.,
through network communications). For example, some requests
submitted to the request processing subsystem 502 may involve the
management of computing resources which may include data objects
stored by the data storage servers 506. The request processing
subsystem 502, for example, may receive and process requests to
modify computing resources. For instance, in some examples, data
objects are logically organized into logical data containers. Data
objects associated with a logical data container may, for example,
be said to be in the logical data container. Requests to the data
processing subsystem 502 may include requests for creating logical
data containers, deleting logical data containers, providing an
inventory of a logical data container, providing or updating access
control policy with respect to one or more logical data containers
and the like.
[0045] The requests may be processed by the management subsystem
504 upon receipt by the request processing subsystem 502. If
applicable, various requests processed by the request processing
subsystem 502 and/or management subsystem 504 may result in the
management subsystem 504 updating metadata associated with data
objects and logical data containers stored in a metadata store.
Additionally, the management subsystem may include an admissions
controller which may update the admissions data 508, described in
greater detail below. Other requests that may be processed by the
request processing subsystem 502 include requests to perform
operations in connection with data objects. The requests, for
example, may include requests to upload data objects to the data
storage service 500, to download data objects from the data storage
service 500, to delete data objects stored by the data storage
service 500 and/or other operations that may be performed.
[0046] Requests processed by the request processing subsystem 502
that involve operations on data objects (upload, download, delete,
e.g.) may include interaction between the request processing
subsystem 502 and one or more data storage servers 506. The data
storage servers 506 may be computer systems communicatively coupled
with one or more storage devices for the persistence of data
objects. For example, in order to process a request to upload a
data object, the request processing subsystem may transmit data to
a data storage server 506 for persistent storage. It is noted,
however, that in some embodiments, client (e.g., customer) computer
systems may transmit data directly to the data storage servers 506
instead of through severs in the request processing subsystem.
[0047] In some embodiments, the request processing subsystem 502
transmits data to multiple data storage servers 506 for the
purposes of redundantly storing the data to allow the
retrievability of data in the event of failure of an individual
data storage server 506 and/or associated data storage device. For
example, in some embodiments, the request processing subsystem uses
a redundancy in coding scheme such as erasure coding to deconstruct
a data object into multiple parts that are stored among the data
storage servers 506. The parts may be configured such that if
access to a certain number of parts is lost, the data object may
nevertheless be reconstructible from the remaining parts that
remain accessible.
[0048] To enable efficient transfer of data between the request
processing subsystem 502 and the data storage servers 506 and/or
generally to enable quick processing of requests, the request
processing subsystem 502 may include one or more databases that
enable the location of data among the data storage servers 506. For
example, the request processing subsystem 502 may operate a key
value store that serves to associate identifiers of data objects
with locations among the data storage servers 506 for accessing
data of the data objects.
[0049] The admissions data 508 may include information
corresponding to the work token buckets or burst token buckets for
the various volumes managed by the data storage service 500 and
global work token buckets for the data storage service 506.
Additionally, the admissions data may contain information
corresponding to the received requests, such as information about
sequential I/O operations included in various received requests.
Returning to FIG. 5, the admissions data 508 may contain data
structures, as described above, containing information indicating a
number of tokens in a particular bucket, a fill rate for a
particular bucket, or other information as described above.
[0050] FIG. 6 illustrates an environment 600 in which various
aspects of admissions control-related operations for block-level
devices that are attachable to one or more computer instances may
be implemented, according to at least one embodiment. Four storage
servers 606 are shown in FIG. 6. A partitioned volume 620B is
illustrated, with three partitions, while three non-partitioned
volumes 620 are shown. In some embodiments in which partitioned
volumes are supported, non-partitioned volumes may simply be
managed as volumes that each comprise a single partition. Both
partitioned and non-partitioned volumes may be attached to multiple
computer instances in the depicted embodiment, e.g., as a result of
various "AttachVolume" API calls. Partitioned volume 620B is
attached to multiple computer instances, while non-partitioned
volume 620 is attached to a single computer instance. A given
computer instance such as 640 may be attached to more than one
multiply-attached volume (such as 620B) in at least some
embodiments.
[0051] The computing resource service provider may provide
customers with the ability to attach a given volume partition 630
or volume to several different computer instances, each of which
could potentially be executing at a different instance host. In
some embodiments in which multiple attachments are supported, a
client-side component of the different instance hosts involved
(i.e., the different instance hosts at which the
concurrently-attached instances are running) may exchange workload
information for each of the attached instances. In other
embodiments, the storage servers 606 involved in implementing the
multiply-attached volumes may collect workload information to be
used for admissions control decisions. For example, a storage
server 606 may collect I/O information of the multiply-attached
volume 620B for use in admissions control decision. In some
embodiments, the storage servers 606 may be able to isolate the
workload metrics for different computer instances that are attached
to the same volume or partition, and use the metrics in various
admissions control determinations, such as removing work tokens
from the global work token bucket, burst token bucket, or work
token bucket as described above.
[0052] FIG. 7 illustrates an environment 700 in which various
aspects of admissions control-related operations for block-level
devices that are attachable to one or more computer instances may
be implemented, according to at least one embodiment. Four
partitioned volumes are illustrated in FIG. 7, volume partitions
730A, 730B, 730C, 730D along with other volumes 720. As described
above in connection with FIG. 6, the partitioned volumes and other
volumes may be attached to one or more computer instances and may
be distributed across one or more data storage serves 706. The data
storage service may track work requests, including I/O information,
across the various data storage servers 706. The information
tracked across the various data servers 706 may be aggregated by
the data storage service and used to generate a burst token bucket
as described above.
[0053] The admissions data 708 may contain burst bucket
information, such as a number of work token remaining in a
particular bucket which is associated with a particular partition.
As illustrated by FIG. 7, the data storage service may maintain, in
the admissions data 708 as described above, information about
volume partitions 730A, 730B, 730C, 730D. The information may
include a size of the volume or volume partition, a fill rate per
second for the volume or volume partition, a number of IOPS (or
PIOPS), and a number of tokens in the burst token bucket. In
various embodiments, the admissions data also contains global work
token bucket information. For example, the admissions data may
include a number of work tokens remaining in the global token
bucket. The global work token bucket may correspond to a particular
data storage server 706 or set of data storage servers 706.
[0054] The admissions data 708 may be maintained by a computer
system for all of the data storage servers 706 for the data storage
service or each data storage server 706 may maintain the admissions
data 708 for the volumes implemented by the data storage server
706. Additionally, a single data storage server 706 may maintain
admissions data for a set of data storage servers 706. For example,
a set of data storage servers 706 may implement a single volume
partitioned over the set of data storage servers 706. One of the
members of the set of data storage servers 706 may maintain the
burst token bucket for the partitioned volume implemented using
computing resources of the set of data storage servers 706.
Although a single member of the set of data storage server 706
maintains the burst token bucket, each data storage serve 706 may
nevertheless maintain its own global work token bucket information
for the data storage server 706.
[0055] FIG. 8 illustrates aspects of an example environment 800 for
implementing aspects in accordance with various embodiments. As
will be appreciated, although a web-based environment is used for
purposes of explanation, different environments may be used, as
appropriate, to implement various embodiments. The environment
includes an electronic client device 802, which can include any
appropriate device operable to send and/or receive requests,
messages or information over an appropriate network 804 and, in
some embodiments, convey information back to a user of the device.
Examples of such client devices include personal computers, cell
phones, handheld messaging devices, laptop computers, tablet
computers, set-top boxes, personal data assistants, embedded
computer systems, electronic book readers and the like. The network
can include any appropriate network, including an intranet, the
Internet, a cellular network, a local area network, a satellite
network or any other such network and/or combination thereof.
Components used for such a system can depend at least in part upon
the type of network and/or environment selected. Protocols and
components for communicating via such a network are well known and
will not be discussed herein in detail. Communication over the
network can be enabled by wired or wireless connections and
combinations thereof. In this example, the network includes the
Internet, as the environment includes a web server 806 for
receiving requests and serving content in response thereto,
although for other networks an alternative device serving a similar
purpose could be used as would be apparent to one of ordinary skill
in the art.
[0056] The illustrative environment includes at least one
application server 808 and a data store 810. It should be
understood that there can be several application servers, layers or
other elements, processes or components, which may be chained or
otherwise configured, which can interact to perform tasks such as
obtaining data from an appropriate data store. Servers, as used
herein, may be implemented in various ways, such as hardware
devices or virtual computer systems. In some contexts, servers may
refer to a programming module being executed on a computer system.
As used herein, unless otherwise stated or clear from context, the
term "data store" refers to any device or combination of devices
capable of storing, accessing and retrieving data, which may
include any combination and number of data servers, databases, data
storage devices and data storage media, in any standard,
distributed, virtual or clustered environment. The application
server can include any appropriate hardware, software and firmware
for integrating with the data store as needed to execute aspects of
one or more applications for the client device, handling some or
all of the data access and business logic for an application. The
application server may provide access control services in
cooperation with the data store and is able to generate content
including, but not limited to, text, graphics, audio, video and/or
other content usable to be provided to the user, which may be
served to the user by the web server in the form of HyperText
Markup Language ("HTML"), Extensible Markup Language ("XML"),
JavaScript, Cascading Style Sheets ("CSS") or another appropriate
client-side structured language. Content transferred to a client
device may be processed by the client device to provide the content
in one or more forms including, but not limited to, forms that are
perceptible to the user audibly, visually and/or through other
senses including touch, taste, and/or smell. The handling of all
requests and responses, as well as the delivery of content between
the client device 802 and the application server 808, can be
handled by the web server using PHP: Hypertext Preprocessor
("PHP"), Python, Ruby, Perl, Java, HTML, XML or another appropriate
server-side structured language in this example. It should be
understood that the web and application servers are not required
and are merely example components, as structured code discussed
herein can be executed on any appropriate device or host machine as
discussed elsewhere herein. Further, operations described herein as
being performed by a single device may, unless otherwise clear from
context, be performed collectively by multiple devices, which may
form a distributed and/or virtual system.
[0057] The data store 810 can include several separate data tables,
databases, data documents, dynamic data storage schemes and/or
other data storage mechanisms and media for storing data relating
to a particular aspect of the present disclosure. For example, the
data store illustrated may include mechanisms for storing
production data 812 and user information 816, which can be used to
serve content for the production side. The data store also is shown
to include a mechanism for storing log data 814, which can be used
for reporting, analysis or other such purposes. It should be
understood that there can be many other aspects that may need to be
stored in the data store, such as page image information and access
rights information, which can be stored in any of the above listed
mechanisms as appropriate or in additional mechanisms in the data
store 810. The data store 810 is operable, through logic associated
therewith, to receive instructions from the application server 808
and obtain, update or otherwise process data in response thereto.
The application server 808 may provide static, dynamic or a
combination of static and dynamic data in response to the received
instructions. Dynamic data, such as data used in web logs (blogs),
shopping applications, news services and other such applications
may be generated by server-side structured languages as described
herein or may be provided by a content management system ("CMS")
operating on, or under the control of, the application server. In
one example, a user, through a device operated by the user, might
submit a search request for a certain type of item. In this case,
the data store might access the user information to verify the
identity of the user and can access the catalog detail information
to obtain information about items of that type. The information
then can be returned to the user, such as in a results listing on a
web page that the user is able to view via a browser on the user
device 802. Information for a particular item of interest can be
viewed in a dedicated page or window of the browser. It should be
noted, however, that embodiments of the present disclosure are not
necessarily limited to the context of web pages, but may be more
generally applicable to processing requests in general, where the
requests are not necessarily requests for content.
[0058] Each server typically will include an operating system that
provides executable program instructions for the general
administration and operation of that server and typically will
include a computer-readable storage medium (e.g., a hard disk,
random access memory, read only memory, etc.) storing instructions
that, when executed by a processor of the server, allow the server
to perform its intended functions. Suitable implementations for the
operating system and general functionality of the servers are known
or commercially available and are readily implemented by persons
having ordinary skill in the art, particularly in light of the
disclosure herein.
[0059] The environment, in one embodiment, is a distributed and/or
virtual computing environment utilizing several computer systems
and components that are interconnected via communication links,
using one or more computer networks or direct connections. However,
it will be appreciated by those of ordinary skill in the art that
such a system could operate equally well in a system having fewer
or a greater number of components than are illustrated in FIG. 8.
Thus, the depiction of the system 800 in FIG. 8 should be taken as
being illustrative in nature and not limiting to the scope of the
disclosure.
[0060] The various embodiments further can be implemented in a wide
variety of operating environments, which in some cases can include
one or more user computers, computing devices or processing devices
which can be used to operate any of a number of applications. User
or client devices can include any of a number of general purpose
personal computers, such as desktop, laptop or tablet computers
running a standard operating system, as well as cellular, wireless
and handheld devices running mobile software and capable of
supporting a number of networking and messaging protocols. Such a
system also can include a number of workstations running any of a
variety of commercially-available operating systems and other known
applications for purposes such as development and database
management. These devices also can include other electronic
devices, such as dummy terminals, thin-clients, gaming systems and
other devices capable of communicating via a network. These devices
also can include virtual devices such as virtual machines,
hypervisors and other virtual devices capable of communicating via
a network.
[0061] Various embodiments of the present disclosure utilize at
least one network that would be familiar to those skilled in the
art for supporting communications using any of a variety of
commercially-available protocols, such as Transmission Control
Protocol/Internet Protocol ("TCP/IP"), User Datagram Protocol
("UDP"), protocols operating in various layers of the Open System
Interconnection ("OSI") model, File Transfer Protocol ("FTP"),
Universal Plug and Play ("UpnP"), Network File System ("NFS"),
Common Internet File System ("CIFS") and AppleTalk. The network can
be, for example, a local area network, a wide-area network, a
virtual private network, the Internet, an intranet, an extranet, a
public switched telephone network, an infrared network, a wireless
network, a satellite network and any combination thereof.
[0062] In embodiments utilizing a web server, the web server can
run any of a variety of server or mid-tier applications, including
Hypertext Transfer Protocol ("HTTP") servers, FTP servers, Common
Gateway Interface ("CGP") servers, data servers, Java servers,
Apache servers and business application servers. The server(s) also
may be capable of executing programs or scripts in response to
requests from user devices, such as by executing one or more web
applications that may be implemented as one or more scripts or
programs written in any programming language, such as Java.RTM., C,
C# or C++, or any scripting language, such as Ruby, PHP, Perl,
Python or TCL, as well as combinations thereof. The server(s) may
also include database servers, including without limitation those
commercially available from Oracle.RTM., Microsoft.RTM.,
Sybase.RTM. and IBM.RTM. as well as open-source servers such as
MySQL, Postgres, SQLite, MongoDB, and any other server capable of
storing, retrieving and accessing structured or unstructured data.
Database servers may include table-based servers, document-based
servers, unstructured servers, relational servers, non-relational
servers or combinations of these and/or other database servers.
[0063] The environment can include a variety of data stores and
other memory and storage media as discussed above. These can reside
in a variety of locations, such as on a storage medium local to
(and/or resident in) one or more of the computers or remote from
any or all of the computers across the network. In a particular set
of embodiments, the information may reside in a storage-area
network ("SAN") familiar to those skilled in the art. Similarly,
any necessary files for performing the functions attributed to the
computers, servers or other network devices may be stored locally
and/or remotely, as appropriate. Where a system includes
computerized devices, each such device can include hardware
elements that may be electrically coupled via a bus, the elements
including, for example, at least one central processing unit ("CPU"
or "processor"), at least one input device (e.g., a mouse,
keyboard, controller, touch screen or keypad) and at least one
output device (e.g., a display device, printer or speaker). Such a
system may also include one or more storage devices, such as disk
drives, optical storage devices and solid-state storage devices
such as random access memory ("RAM") or read-only memory ("ROM"),
as well as removable media devices, memory cards, flash cards,
etc.
[0064] Such devices also can include a computer-readable storage
media reader, a communications device (e.g., a modem, a network
card (wireless or wired), an infrared communication device, etc.)
and working memory as described above. The computer-readable
storage media reader can be connected with, or configured to
receive, a computer-readable storage medium, representing remote,
local, fixed and/or removable storage devices as well as storage
media for temporarily and/or more permanently containing, storing,
transmitting and retrieving computer-readable information. The
system and various devices also typically will include a number of
software applications, modules, services or other elements located
within at least one working memory device, including an operating
system and application programs, such as a client application or
web browser. It should be appreciated that alternate embodiments
may have numerous variations from that described above. For
example, customized hardware might also be used and/or particular
elements might be implemented in hardware, software (including
portable software, such as applets) or both. Further, connection to
other computing devices such as network input/output devices may be
employed.
[0065] Storage media and computer readable media for containing
code, or portions of code, can include any appropriate media known
or used in the art, including storage media and communication
media, such as, but not limited to, volatile and non-volatile,
removable and non-removable media implemented in any method or
technology for storage and/or transmission of information such as
computer readable instructions, data structures, program modules or
other data, including RAM, ROM, Electrically Erasable Programmable
Read-Only Memory ("EEPROM"), flash memory or other memory
technology, Compact Disc Read-Only Memory ("CD-ROM"), digital
versatile disk (DVD) or other optical storage, magnetic cassettes,
magnetic tape, magnetic disk storage or other magnetic storage
devices or any other medium which can be used to store the desired
information and which can be accessed by the system device. Based
on the disclosure and teachings provided herein, a person of
ordinary skill in the art will appreciate other ways and/or methods
to implement the various embodiments.
[0066] The specification and drawings are, accordingly, to be
regarded in an illustrative rather than a restrictive sense. It
will, however, be evident that various modifications and changes
may be made thereunto without departing from the broader spirit and
scope of the invention as set forth in the claims.
[0067] Other variations are within the spirit of the present
disclosure. Thus, while the disclosed techniques are susceptible to
various modifications and alternative constructions, certain
illustrated embodiments thereof are shown in the drawings and have
been described above in detail. It should be understood, however,
that there is no intention to limit the invention to the specific
form or forms disclosed, but on the contrary, the intention is to
cover all modifications, alternative constructions and equivalents
falling within the spirit and scope of the invention, as defined in
the appended claims.
[0068] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the disclosed embodiments
(especially in the context of the following claims) are to be
construed to cover both the singular and the plural, unless
otherwise indicated herein or clearly contradicted by context. The
terms "comprising," "having," "including" and "containing" are to
be construed as open-ended terms (i.e., meaning "including, but not
limited to,") unless otherwise noted. The term "connected," when
unmodified and referring to physical connections, is to be
construed as partly or wholly contained within, attached to or
joined together, even if there is something intervening. Recitation
of ranges of values herein are merely intended to serve as a
shorthand method of referring individually to each separate value
falling within the range, unless otherwise indicated herein and
each separate value is incorporated into the specification as if it
were individually recited herein. The use of the term "set" (e.g.,
"a set of items") or "subset" unless otherwise noted or
contradicted by context, is to be construed as a nonempty
collection comprising one or more members. Further, unless
otherwise noted or contradicted by context, the term "subset" of a
corresponding set does not necessarily denote a proper subset of
the corresponding set, but the subset and the corresponding set may
be equal.
[0069] Conjunctive language, such as phrases of the form "at least
one of A, B, and C," or "at least one of A, B and C," unless
specifically stated otherwise or otherwise clearly contradicted by
context, is otherwise understood with the context as used in
general to present that an item, term, etc., may be either A or B
or C, or any nonempty subset of the set of A and B and C. For
instance, in the illustrative example of a set having three
members, the conjunctive phrases "at least one of A, B, and C" and
"at least one of A, B and C" refer to any of the following sets:
{A}, {B}, {C}, {A, B}, {A, C}, {B, C}, {A, B, C}. Thus, such
conjunctive language is not generally intended to imply that
certain embodiments require at least one of A, at least one of B
and at least one of C each to be present.
[0070] Operations of processes described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. Processes described herein (or
variations and/or combinations thereof) may be performed under the
control of one or more computer systems configured with executable
instructions and may be implemented as code (e.g., executable
instructions, one or more computer programs or one or more
applications) executing collectively on one or more processors, by
hardware or combinations thereof. The code may be stored on a
computer-readable storage medium, for example, in the form of a
computer program comprising a plurality of instructions executable
by one or more processors. The computer-readable storage medium may
be non-transitory.
[0071] The use of any and all examples, or exemplary language
(e.g., "such as") provided herein, is intended merely to better
illuminate embodiments of the invention and does not pose a
limitation on the scope of the invention unless otherwise claimed.
No language in the specification should be construed as indicating
any non-claimed element as essential to the practice of the
invention.
[0072] Embodiments of this disclosure are described herein,
including the best mode known to the inventors for carrying out the
invention. Variations of those embodiments may become apparent to
those of ordinary skill in the art upon reading the foregoing
description. The inventors expect skilled artisans to employ such
variations as appropriate and the inventors intend for embodiments
of the present disclosure to be practiced otherwise than as
specifically described herein. Accordingly, the scope of the
present disclosure includes all modifications and equivalents of
the subject matter recited in the claims appended hereto as
permitted by applicable law. Moreover, any combination of the
above-described elements in all possible variations thereof is
encompassed by the scope of the present disclosure unless otherwise
indicated herein or otherwise clearly contradicted by context.
[0073] All references, including publications, patent applications
and patents, cited herein are hereby incorporated by reference to
the same extent as if each reference were individually and
specifically indicated to be incorporated by reference and were set
forth in its entirety herein.
* * * * *